Technical Field
The present invention relates to an apparatus for processing a substrate, such as a semiconductor wafer.
Background Art
Chemical mechanical polishing (CMP) apparatuses for polishing a surface of a substrate have been known in production of semiconductor devices. In a CMP apparatus, a polishing pad is pasted on the upper surface of a polishing table to form a polishing surface. The CMP apparatus presses a polishing target surface of a substrate held by a top ring against the polishing surface, and rotates the polishing table and the top ring while supplying a slurry as a polishing liquid to the polishing surface. Accordingly, the polishing surface and the polishing target surface are relatively moved with the surfaces being in sliding contact, and the polishing target surface is polished.
In a typical CMP apparatus, the polishing table or the polishing pad is larger than a substrate to be polished. While the substrate is held by the top ring such that a polishing target surface faces downward, the substrate is polished. The polished substrate is cleaned by a sponge member, such as of polyvinyl alcohol (PVA), rotating in contact with the substrate, and is then dried.
The applicant of the present application has filed an application on a technique where, after polishing of a substrate, a finishing process unit that presses a contact member having a smaller diameter than the substrate against the polished substrate to relatively move the contact member is provided in a CMP apparatus separately from a main polishing unit, and the substrate is slightly and additionally polished and cleaned (Japanese Patent Laid-Open No. 8-71511).
The CMP apparatus includes: a polishing unit for performing a substrate polishing process; a cleaning unit for performing a substrate cleaning process and drying process; and a load/unload unit that passes a substrate to the polishing unit and receives the substrate having been subjected to the cleaning process and the drying process by the cleaning unit. The CMP apparatus further includes a conveyor mechanism that conveys the substrate in the polishing unit, the cleaning unit, and the load/unload unit. The CMP apparatus sequentially performs various types of processes including polishing, cleaning and drying, while allowing the conveyor mechanism to convey the substrate. A cleaning unit has been disclosed that brings a cleaning member into contact with a semiconductor substrate to scrub and clean the substrate, and then brings the cleaning member having been cleaned into contact with a flat and rough surface of a correction member to perform self-cleaning (see Japanese Patent Laid-Open No. 9-92633).
In some cases, a substrate processing apparatus may be provided with a buff process module. The buff process module applies at least one of a buff-polishing process and a buff-cleaning process to a substrate. The buff-polishing process is a process that relatively moves a wafer and a buff pad against each other while the buff pad is in contact with the wafer, and causes a slurry to intervene between the wafer and the buff pad, thereby polishing and removing unwanted portions on a processing target surface of the wafer. On the other hand, the buff-cleaning process is a process that relatively moves the wafer and the buff pad against each other while the buff pad is in contact with the wafer, and causes a cleaning process liquid (a chemical solution, or the chemical solution and pure water) to intervene between the wafer and the buff pad, thereby removing contaminants on the surface of the wafer or modifying the property of the processing target surface.
Unfortunately, continuation of the buff-polishing process and the buff-cleaning process by the buff pad clogs the surface of the buff pad, thereby reducing the polishing performance and the cleaning performance. Accordingly, in order to renew the performance of the buff pad, conditioning which is referred to as a dressing process is required. The conditioning is performed by a conditioner. The conditioner includes a dressing table, and a dresser installed on the dressing table. The dressing table can be rotated by a drive mechanism. The dresser may be formed of a diamond dresser or a brush dresser, or a combination of these dressers.
When the buff pad is conditioned, the buff process module swings the buff arm such that the buff pad reaches a position facing the dresser. The buff process module rotates the dressing table about a predetermined rotation axis while rotating the buff head, and presses the buff pad against the dresser, thereby applying the dressing process to the buff pad (conditioning).
The attached FIG. 38 does not show the buff pad, but shows the dresser 4-33A used for the polishing unit. The polishing unit adopts the dresser 4-33A having a smaller diameter than a polishing pad 4-10, which has a larger diameter. In the dressing process, a process liquid is dropped from a process liquid supply nozzle 4-32A onto the center of the polishing pad 4-10, and the dresser 4-33A moves to and from along a radius of the polishing pad 4-10. This movement is combined with the rotational motion of the polishing pad 4-10, thereby applying the dressing process to the entire surface of the polishing pad 4-10. In many cases, the process liquid for the polishing pad 4-10 may be a liquid with a high viscosity, such as a slurry. Unfortunately, solid components made from the process liquid adhere and deposit into grooves formed on the surface of the polishing pad 4-10. Such contamination cannot be removed only by the dressing process. Accordingly, a cleaning mechanism referred to as an atomizer 4-34A is used to clean the surface of the polishing pad 4-10. Here, as shown in FIG. 36B, the atomizer 4-34A is a cleaning mechanism that can jet a high pressure liquid or a mixture of the liquid and a gas to the polishing pad 4-10. As shown in FIG. 38A, the atomizer 4-34A is disposed for a radius portion of the polishing pad, the polishing pad 4-10 is rotated at the same time of jetting of the high pressure cleaning fluid, thereby removing the contamination adhering and depositing in the grooves of the polishing pad 4-10.
In a finishing process unit, in order to bring a contact member into contact at a high pressure and improve the cleaning effect and to increase the polishing speed, a substrate is required to be held by a table that is in contact with the entire rear surface of the substrate. In the case where a substrate is supported by a table that supports the substrate at an entire surface, abrasive grains and polishing by-products (organic residues) sometimes accumulate on the table surface, and contaminates the substrate to be processed. Accordingly, the table that supports the substrate, and structural components (a substrate conveyor mechanism etc.) accompanying the table are always required to have high cleanliness.
The present invention has an object to improve the degree of cleaning of a table on which a substrate is mounted and structural components accompanying the table during a polishing process.
The conventional technique only cleans the buff pad by relatively moving the buff pad and the dresser against each other. The cleaning process can thus be achieved to a certain extent, only with which the buff pad however cannot sufficiently cleaned in some cases.
Accordingly, the invention of the present application has an object to provide a buff process module having an enhanced buff pad cleaning power.
If the buff process module in the aforementioned example is provided with an atomizer, the following problem occurs. That is, in the example of the conventional technique in FIGS. 38A and 38B, the polishing pad 4-10 has a larger diameter than the dresser 4-33A has. Consequently, in the example of FIGS. 38A and 38B, the atomizer 4-34 can be installed so as to face an area on the surface of the polishing pad 4-10 that is not covered with the dresser 4-33A.
On the contrary, in the buff process module, the buff pad has a size equivalent or smaller than the dresser. Consequently, in the buff process module, the entire surface of the buff pad is covered with the dresser. As a result, unlike the conventional technique, it is difficult to install the atomizer in the buff process module.
Accordingly, the invention of the present application has an object to provide an atomizer applicable to a buff process module that includes a buff pad having a size equivalent to or smaller than a dresser.
Furthermore, the aforementioned conventional technique has the following problems. That is, when the dresser of the conditioner continues applying the dressing process to the buff pad, contamination accumulates. Consequently, the surface of the dresser is required to be periodically cleaned (dress-rinsed). At this time, the surface of the dresser and the surface of the wafer, which is a processing target object, reside in the substantially same surface. This arrangement is adopted because the buff-polishing process, the buff-cleaning process and the dressing process can be achieved only by parallel (e.g., horizontal) movement of the buff pad. Unfortunately, if no measures are taken for cleaning the dresser, the cleaning liquid jetted toward the dresser is dispersed to the wafer and contaminates the wafer.
Accordingly, the invention of the present application has an object to provide a conditioner that does not contaminate the wafer on the buff table adjacent to the dresser even when the dresser is cleaned (dress-rinsed).
Furthermore, the aforementioned cleaning unit adopts only one cleaning method. Consequently, a cleaning target member cannot be sufficiently cleaned in some cases. For example, if grooves are formed on the cleaning target member, particles having entered the grooves (e.g., a slurry used for polishing, polishing dust on a substrate, etc.) cannot be sufficiently removed only by brushing in some cases. In such cases, it is preferred that in addition to the process of dressing the cleaning member using a brush or the like, pressurized water be separately jetted to the cleaning member by the atomizer to sufficiently remove the particles. That is, it is preferred that two or more types of conditioning be performed. If the two or more types of conditioning are to be performed, multiple conditioning devices are required to be installed for performing the respective types of conditioning. In this case, the installation space of the devices increases with the number of the conditioning devices. The increase, in turn, increases the entire size of the facility. Furthermore, the cleaning member is required to be moved between these devices. Consequently, the processing time is increased by a time required for the movement. These problems are commonly found not only in the cleaning unit but also in a final polishing unit that performs final polishing after polishing by a main polishing unit.